A novel fluorescence-based method for the determination of Zuranolone using Tinopal CBS-X in the pharmaceutical formulation and spiked human plasma.

Zuranolone is a neuroactive steroid modulating GABA-A receptors, providing fast and effective treatment for depressive disorders. Despite its therapeutic promise, Zuranolone lacks strong chromophores or fluorophores, complicating its quantitative analysis using traditional optical methods. This study presents a validated spectrofluorimetric method for Zuranolone determination, utilizing Tinopal CBS-X, a fluorescent dye, as a probe. Under optimized conditions, a stable ion-pair complex forms between Tinopal CBS-X and Zuranolone, with characteristic florescence emission signal at 520 nm. The method demonstrates high sensitivity with a linear range of 5-200 ng/mL, a limit of detection of 1.50 ng/mL, and a limit of quantification of 4.50 ng/mL. The method was rigorously validated according to ICH guidelines, demonstrating high accuracy (recoveries between 98.50 and 100.66%), intra- and inter-day precision (RSD < 2%). The method's selectivity was confirmed by standard addition technique testing which highlighted noninterference from pharmaceutical excipients. The method showed good linearity, precision, and accuracy, and was successfully applied to the quantification of Zuranolone in commercial formulations. These findings suggest potential utility in therapeutic drug monitoring and quality control settings, offering a simple, rapid, and cost-effective tool for ensuring accurate dosing and formulation consistency, ultimately supporting better patient care.